Optical networks are employed to support the demand for high-speed, high-capacity advanced telecommunications and data networks. These optical networks commonly utilize optical dense wavelength division multiplexing (DWDM) to exploit the available optical spectrum. In optical DWDM, data is modulated onto several different carrier waves of different wavelengths, commonly referred to as channels or channel wavelengths.
Many optical networks employ optical nodes that occur at branch points of the optical network. Often, these nodes employ Reconfigurable Optical Add Drop Multiplexer (ROADM) devices that allow for the removal or addition of one or more channel wavelengths at a node.
In order to realize a ROADM device, a wavelength selective switch (WSS) may be employed for the routing of the channel wavelengths. In many WSS architectures, an optical deflection device, such as a liquid crystal on silicon (LCoS) phased array switching engine, may be used to select a channel wavelength for routing to a desired output port of the WSS. For example, routing of a channel wavelength of a DWDM signal to a drop port results in that channel wavelength being dropped from the incoming DWDM signal.
In current and future optical networks, a signal baud rate may be set very close to channel spacing so as to improve (and possibly maximize) spectral efficiency. Due to this close association, there is the potential of loss of signal information unless the passband of the channel can be maximized, while at the same time being careful to minimize crosstalk from adjacent channels.